1. Field of the Invention
The invention relates to a device for processing video signals, comprising a noise reduction arrangement and a contour correction arrangement. The invention also relates to a method of noise reduction and contour correction.
2. Description of the Related Art
When generating, processing and transmitting video signals, noise reducers are used which eliminate noise signals in the video signal as much as possible. To compensate for losses which occur in high-frequency signal components, a contour correction is often performed after the noise reduction. Since the number of circuit components for a contour correction is relatively small as compared with the number of circuit components for noise reduction, noise reduction and contour correction are preferably performed in a common circuit arrangement. A device which combines both the functions of noise reduction and contour correction, as well as other functions is commercially available as type MNR11 from Philips BTS and described in a brochure.
Video signals are generally not only disturbed by noise signals but also have color offsets which are due to, for example different phase delay times. These color offsets can generally be eliminated completely by means of an arrangement for color correction. Because of their complexity, color correction arrangements are generally independent apparatuses. As has been proved in practice, no satisfactory results with the color correction could be achieved when a color correction apparatus and a combined device as described in the opening paragraph, performing both noise reduction and contour correction, were used simultaneously.